The present invention relates generally to the field of catheters. More specifically, the present invention relates to a hollow catheter which may be used as a guiding sheath for balloon catheters, or for diagnostic purposes to conduct radio-opaque dyes to particular areas of the body, as for example, in angiography.
Percutaneous transluminal coronary angioplasty (PTCA) is a procedure for treating patients having stenotic, or constricted blood flow regions in the coronary arteries and has become a widely accepted therapeutic alternative to coronary bypass surgery. Performing a coronary angioplasty involves the difficulty of inserting a dilatation balloon catheter into the obstructed coronary artery. Because most balloon dilatation catheters are too flexible for direct insertion into a patient's blood vessel, the standard angioplasty process begins with the insertion of a guiding catheter, or sleeve into the obstructed vessel, under a local anesthesia. The guiding catheter is designed to provide a conduit through which a balloon dilatation catheter may be passed. In addition, the guiding catheter may be used as a diagnostic catheter to conduct radio-opaque dyes into the localized area to be dilated, so as to aid in determining when blood flow has been restored to an acceptable level.
The guiding catheter may be preformed into a bent configuration so as to better guide a dilatation catheter into the proper coronary orifice. The relatively stiff shaft of the guiding catheter is designed to provide the longitudinal support necessary to maintain tip stability as the balloon dilatation catheter is advanced into the appropriate coronary artery. Present guiding/diagnostic catheters for femoral PTCA can be thought of as being categorized into one of three general configurations: Judkins shapes, Amplatz shapes, and multipurpose shapes. The Judkins left catheter is commonly used for directing a balloon catheter into the left anterior descending artery, while the Judkins right catheter is adapted for use when treating the right coronary artery. The Amplatz catheter is most suited for use in the circumflex and right coronary arteries, and the multipurpose shapes are generally employed for vein grafts and some right coronary lesions. The purpose of the guiding catheter is not only to direct the balloon catheter into the diseased coronary artery, but also to provide a launching pad for exerting some pressure on the balloon catheter to force it through some very tight stenoses.
Once a guiding catheter is inserted into the femoral artery and positioned in the aorta proximate to the proper coronary orifice, a balloon dilatation catheter may be inserted and advanced into the diseased artery. However, sometimes the tip of the guiding catheter is advanced too far into the artery, impairing the blood supply distal to the guiding catheter. In addition, because the size and shapes of the various arteries vary substantially from patient to patient, it is often times impossible for the surgeon to place even the smallest guiding catheter proximate to the diseased artery without severely impeding blood flow.
FIG. 1 is illustrative of a presently available guiding catheter 10, having a left Judkins shape, in which the end 12 is positioned proximate the orifice 14 to the left main artery 16. Usually, the guiding catheter 10 is either pre-formed in one of the aforementioned configurations, as illustrated here, or is bent by the surgeon prior to introduction into the patients blood vessel. By altering the orientation of the tip 12 of the guiding catheter 10 with respect to the desired coronary orifice 14, the guiding catheter 10 can significantly aid in the subselective placement of a balloon dilatation catheter (not shown). As illustrated in FIG. 1, as the guiding catheter 10 is advanced through the aorta 18 the tip 12 is forced into the left main artery 16. One bend 20 will stabilize the catheter 10 with respect to the aorta 18 while the more distal bend 22 rests at the arterial orifice 14. As more clearly illustrated in FIG. 2, the guiding catheter 10 can block a substantial portion of the coronary orifice 14, thereby decreasing the amount of blood flow to the more distal vessels 24, 26. Depending on the diameter of the blood vessel 16, such blockage can severely impair blood flow therethrough. This creates a further dilemma for the surgeon, as the angioplasty procedure must be hastened or the guiding catheter 10 be partially withdrawn so as to increase the amount of blood flow.
Another common occurrence, especially in the right coronary artery, is the presence of stenotic lesions proximate the arterial orifice. As schematically illustrated in FIG. 15, the right coronary artery 28 is often times of the same diameter as even the smallest presently available guiding catheter 10. Thus, when the guiding catheter 10 is inserted through the aorta 18 and into the right coronary artery 28, it is blocked from further entry by the stenosis 30. Stenoses, in general are of varying degrees, shapes and sizes. When a stenosis 30 is present proximate to the arterial orifice 32, and the guiding catheter 10 is of the same size as that of the artery 28, then blood flow through that artery 28, as well as the more distal arteries (not shown), will be totally occluded. This is most undesirable in that the patient will then begin to experience chest pains, a drop in blood pressure, and may necessitate the emergency bypass surgery.
After performing a coronary angioplasty, it is often times desireable to ascertain the amount and rate of blood flow through the once-restricted vessel. Blood is not normally visible on an X-ray image because it has about the same radio density as that of the surrounding tissue. In angiographic procedures, the outlines of blood vessels are made visible on an X-ray image by injecting a bolus of contrast medium directly into the bloodstream in the region to be investigated. The injection of such a contrast medium into a blood vessel enables the circulation pattern to be made locally visible. Because the contrast medium is rapidly diluted in the blood circulation, an X-ray photo or a series of such photos must be taken immediately after the injection. On a sequential record of the X-ray image, the progress of the contrast medium can be followed so as to enable one to detect obstructions as well as to estimate blood flow in certain blood vessels. Preferably, the radio-opaque dye may be injected through the same guiding catheter used to guide the dilatation catheter. However, use of this catheter is accompanied by the same flow restrictions. This is significant in that the measurement of the injected dye may produce faulty data due to the decrease in normal blood flow caused by the guiding catheter.